This invention relates to an electric apparatus having a silent alarm function, and more particularly to an electric apparatus with silent alarm which generates a vibration at an alarm time.
A silent alarm is sometime employed in a timepiece or pager. A conventional clock with silent alarm is shown in FIG. 14. A vibration alarm 27, which often sets under a pillow, holds a vibration alarm motor 28 that has an eccentric weight 29 on the rotary shaft and that is electrically connected to a clock 25 through a connection cord 26. The vibration alarm motor 28 rotates at an alarm set point time, and the vibration alarm 27 is vibrated by the centrifugal force of the eccentric weight 29 generated by the turn thereof to let a person know the alarm time.
On the other hand, a variety of wrist watches with silent alarm have heretofore been proposed of a type in which a bar, a hammering piece or a lever gives stimulation to the skin to let a person know a set point time. Furthermore, Japanese Utility Model Laid-Open No. 188185/1982 discloses a wrist watch of the vibration type in which a hammering bar 30 is actuated by a gear 33 and the like and an impact receiving piece 32 directly coupled to a vibration plate 31 is knocked repetitively to generate vibration which stimulates the skin to let a person know a set point time.
The system which generates vibration by rotating the eccentric weight has been employed for clocks and pocket bells that have relatively large sizes as described above. However, such a system has not been adapted to the wrist watches yet, and a concrete structure therefor has not been proposed, either, since the alarm motor for generating the vibration becomes bulky and extra space is required for the eccentric weight,
Among the conventional wrist watches with silent alarm, those of the type which stimulates the skin by a bar, a hammering piece or a level encounter limitations in the outer structure, lack general applicability, and are liable to lose water-proof capability. Furthermore, the wrist watches which stimulate the skin give an uncomfortable feeling to the person wearing them. Further, the device of the type of vibration shown in FIG. 15 is fundamentally the same as the system that gives stimulation by a bar or the like; i.e., stimulation is given repetitively very many times maintaining short intervals, and problems the same as those mentioned above are involved. In this case, furthermore, the hammering bar continuously knocks the impact receiving piece, whereby a knocking noise is generated which is not a silent alarm and the durability is deteriorated. Moreover, an increased number of parts is disadvantageous for realizing the wrist watch with silent alarm in a small size and in a reduced thickness.